StarSimu - How to create the model

How to create the model

StarSimu is a file that runs on Microsoft® Excel. Here follow the few instructions you need to compute a polytropic model also on a different electronic spreadsheet program. To create a worksheet for this calculation, invoke the program on your computer and refer to the settings listed below. Once the worksheet is completed, you can change any value or formula, and all quantities depending on it are automatically recalculated.

Here are the instructions to create the model:

1) Global setting

Assign the scientific (or exponential) format, with one decimal digit (in this format, a number like "130" looks like "1.3E +02", that means "1.3*10^2", where "10^2" and, more generally, "10^n", is equivalent to "1" followed by n zeros).
Align the content of a cell at the center of its column.

2) Labels

Enter into the cells located at the corresponding coordinates the various labels visualized as bold face in the white dwarf's screenshot (see "Modeling a white dwarf").
Assign to the cells C3, C5, F1, F5 the decimal format, with 4, 2, 1, 0 decimal digits, respectively.

3) Numerical values

Enter the input values: we suggest to put "1.0E +11" in cell C1, "0.8" in cell F1, "1.333.." in cell C3, and "4.94E +14" in cell F3.
Enter "0.0E +00" into cells A8, D8, I8, and J8.

4) Formulas


*Cell*	*Formula*
B8 C8 A9 E8	=C1 =F3B8^C3 =A8 + $F$1100000 =A8/($F$5*100000)

Copy the content of cells A9 and E8 into cells A10..A1000 and E9..E1000, respectively


D9 H8	=D8 + 4.189B8(A9^3-A8^3) =D8/($C$5*2E+33)

Copy the content of cells D9 and H8 into cells D10..D1000 and H9..H1000, respectively


C9 G8	=C8 - 6.673E-8B8(A9-A8)*D9/A9^2 =C8/$C$8

Copy the content of cells C9 and G8 into cells C10..C1000 and G9..G1000, respectively


B9 F8	=(C9/$F$3)^(1/$C$3) =B8/$B$8

Copy the content of cells B9 and F8 into cells B10..B1000 and F9..F1000, respectively


I9 J9	=SE(I8=0;SE(C9>0;0;(D9+D8)/2);1E-90) =SE(J8=0;SE(C9>0;0;(A9+A8)/2);1E-90)

Copy the content of cells I9 and J9 into cells I10..I1000 and J10..J1000, respectively


C5 F5	=MAX(I8:I1000)/2E+33 =MAX(J8:J1000)/100000

5) Graph

Select "X-Y" when the menu asks for the type of graph you want.
Choose as ascissa cells in column E, starting from E8 up to the cell corresponding to the stellar surface (with the current parameter choice this is cell E895).
Choose, for three different ordinates, cells in columns F, G, and H, respectively, again starting from those at line 8 up to those corresponding to the surface.

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